Field of the Invention
Disclosed embodiments relate generally to vehicle systems and control processes, such as railway systems including trains travelling in a track or rail network, and in particular to a train control system and method that provide improved train control in railway networks, such as in connection with train control predictions and modeling, approaching stop targets, and the like.
Description of Related Art
Vehicle systems and networks exist throughout the world, and, at any point in time, a multitude of vehicles, such as cars, trucks, buses, trains, and the like, are travelling throughout the system and network. With specific reference to trains travelling in a track network, the locomotives of such trains are typically equipped with or operated using train control, communication, and management systems (e.g., positive train control (PTC) systems), such as the I-ETMS® of Wabtec Corp. These computer-controlled train management systems have on-board computers or controllers that are used to implement certain train control and management actions for ensuring safe and effective operation of the train.
A problematic aspect of PTC is that it can interfere with the ability of the crew (or other train control systems, such as an energy management system) to control the train. For example, PTC can interfere with the ability of the crew to control the train to approach a stop target, such as a switch or signal. The crew typically desires to stop the train as close to the stop target as possible, for example, in order to more clearly see a signal indication or switch position at the stop target, or to position the train such that its rear end is not extending beyond a track circuit, switch, or siding. However, this goal often conflicts with PTC behavior, which attempts to prevent the train from overrunning the stop target. For example, PTC includes a safety offset at which the train should be stopped before the stop target, and PTC is typically conservative in assumptions that it makes about current train control settings.
PTC does not know what future actions may be taken by the crew. If the crew throttles up one notch to creep closer to a stop target ahead, the crew knows that they plan to reduce the throttle in the near future, e.g., in a few seconds, as speed begins to increase. The crew may also know that they plan to apply locomotive independent brakes in the near future to help slow or stop the train. PTC does not know that the crew plans to take these future actions and, from a safety perspective, assumes that the control settings, e.g., the throttle up, will not be changed. For example, PTC may assume that the control settings do not change for a predetermined time period, e.g., 75 seconds. This puts PTC at a disadvantage in predicting and modeling the train behavior. Moreover, because PTC can only control the penalty brakes, it is forced to model train behavior that does not match real world behavior and actual train handling by the crew. PTC thus predicts a much larger increase in speed based on the crew's actions than was intended by the crew, which results in a longer braking curve and, ultimately, PTC issuing warnings and performing enforcement actions. This behavior by PTC makes it more difficult for the crew to approach a stop target and stop close to the target.
Similarly, PTC may not know how an energy management system (or other systems that control the train) plans to control the train during a future period of time. Accordingly, PTC predictions and modeling may be rendered less accurate and/or unnecessary nuisance warnings may be issued during implementation of an energy management plan.
For at least these reasons, there is a need in the art for an improved train control system and method.